Signaling apparatus for telephone-switchboards.



No. 774,332. PATENTBD NOV. 8. 1904.

F. R; MoBBRTY.

SIGNALING APPARATUS FOR TELEPHONE SWITGHBOARDS.

APPLICATION FILED DEO.26, 1899.

NO MODEL.

My a UNITED STATES FRANK R. MGBERTY, OF EVAN STON, ILLINOIS, ASSIGNOR TO WESTERN ELEC- Yatented November 8, 1904.

PATENT OFFICE.

TRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SIGNALING APPARATUS FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 774,332, dated November 8, 1904.

Application filed December 26, 1899. Serial No. 741.575. (N model.)

T0 all whom it y Concern! eluded serially in the line-circuit between the Beitknown thatI,FRANKR.MoBERTY,acitispringjack of the line and the substation. zen of the United States, residing at Evanston, The signaling-battery is connected in a bridge O 7 in the countyof Cook and State of Illinois,have of the line between the spring-jack and the 5 invented a certain new and useful Improvewinding of the relay, above referred to. This ment in Signaling Apparatus for Telephonebridge is of high impedance to prevent the Switchboards, of which the following is a full, shunting oftelephone-currents. I preferably clear, concise, and exact description. provide a second winding of high impedance 5 5 My invention relates to the signaling appafor the line-signal magnet before referred to 10 ratus of telcphone-switchboards for indicating and include this winding in the bridge with at the switchboard signals transmitted from the signaling-battery. The battery or other the substations 0f the diflerent telephone-lines source of current which is designed to supterminating in the switchboard. ply the substation-transmitters may in ac- 60 In a former patent, N 0. 680,879, dated Aucordance with the usual practice be the same gust 20, 1901, I have described a system of battery as that used for operating the linesignals in which a subsidiary line-signal perrelay before referred to and may be conmanently associated with each telephone-line nected in a bridge of the plug-circuit beand a subsidiary clearing-out or supervisory tween the windings of a repeating-coil. The 5 signal temporarily associated with the line magnet in the line-circuit may serve to conduring connection arecontrolled by a single trol signals in accordance with the plan derelay included in the line-circuit and respondscribedin Patent No. 669,708, granted March ing to currents existing in it during the use 12, 1901, to Charles E. Scribner that is to of the telephone-line. say, a-line-signal may be included in a local 7 My present invention is a modification of circuit with a battery and a resistance, said 2 5 the invention in the before-mentioned prior circuit being controlled by switch-contacts oppatent, and has for its object to adapt the sigerated by the line-signal magnet or relay, and nal-controlling relay for use in telephone-exa supervisory signal associated with the plug change systems in which current for exciting by which connection is made with the line may or operating the substation telephone-transbe included in ashunt of the line-signal closed 3 mitters is supplied through the telephonein registering contacts of the plug and springlines from a common source at the central stajack. The substation apparatus will be protion during the use of the lines, the temporary vided with the usual telephone-switch to deconnection of the source of current-supply betermine the flow of current in the line. When ing made through impedance-coils or repeatthe substation-telephone is removed from its 35 ing coils of comparatively low resistance. switch-hook, the circuit of the signaling-bat- W'ith such a system if a high-resistance sigtery is closed and current therefrom fiows nal-controlling magnet were merely included through the coils of the line-relay, exciting in a bridge of the line with the spring-jack the relay and causing the same to close the 10- between such bridge and the substation, as cal circuit containing the subsidiary line-sig- 4 shown in my Patent No. 680,879, for example, nal. When in response to the signal connecthe connection of the battery with the line at tion is made with the line by the insertion of the spring-jack through the low-resistance rea plug in the spring-jack thereof, the battery peating-coil in the plug-circuit would shunt is applied to the line through the low-resist- 9 the current from the signal-magnet and imance windings of the repeating-coil in the 45 pair the working of the system. plug-circuit and flows out to the substation'to In accordance with my invention the signalexcite the transmitter. This current traverses controlling magnet or relay has a winding inthe low-resistance winding of the line-relay and maintains the excitation of said relay, although the high-resistance winding thereof, which may have been included in the permanent bridge with the signaling-battery, is shunted by the low-resistance repeating-coil during the connection. While the line-relay remains excited, both the parallel circuits containing the subsidiary signals are closed and neither signal receives suificient current for its excitation; but when at the end of the conversation the subscriber replaces his teleph one on its hook the branch containing the linesignal will be opened, so that increased current will flow through the other branch containing the supervisory signal, causing the latter to be displayed.

I have diagrammatically illustrated a form of my invention in the accompanying drawing, which represents two substations connected by metallic circuit-lines with springjacks upon a telephone-switchboard and with relays controlling signal-lamps, together with a pair of connecting-plugs and their accessory appliances in the switchboard.

The substations-for example, substation A-are each equipped with a telephone-receiver (r and a transmitter a, a signal-bell (6 and. a telephone-switch (4 which is adapted to close the circuit through the telephone. The hell (0 should be of high resistance say of five thousand ohms-for the purpose of practically severing the connection between the line-wires in respect to currents adapted to operate the central-station relay. The substation apparatus is connected by line-wires 1 and 2 with a terminal spring-jack 7) in the switchboard at the central station C, the different conductors extending to the contactsprings cl and (Z, respectively. of the springjack. One helix, 6, of the line-relay f is included in conductor 1 before the latter is connected with the spring-jack b. The other helix, e, of the relay is included in an extension from conductor 1 to one pole of a battery g, which is common to the different telephonelines of the exchange and serves to supply them with current both for operating the relays and for operating the substation-transmitters. Conductor 2 of the line is connected with the other pole of the same battery, an impedance-coil it being interposed in the conductor for the purpose of balancing the linecircuit and preventing the conduction of telephonic or voice currents between the different lines. The coil 0 of the relay is shunted by a resistance-coil e wound non-inductively. The contacts 6 e of the relay control a local circuit 3 4, including a line-lamp Z, resistancecoil Z1, and a battery placed near the spring-jack 7), so as to be perma nently associated therewith. Each springjaclt is furnished with a contact-ring (Z in addition to its line-contacts (Z and (Z. The ring (6 of the jack 6 constitutes one terminal of a conductor 5, extending to the portion 4 of the The line-lamp is l local circuit 3 4. and connected therewith between the resistance-coil and the contacts 6 e" of the line-relay.

The usual pairs of connecting-plugs m and m are provided for the operator for use in connecting different lines together by means of their spring-jacks. Each plugis constructed with three contact-surfaces insulated from each other, 92 72 and 42 respectively, which are adapted to come into connection with the spring-jack contacts (Z, OZ, and (Z The pieces a; n of the two plugs m m are connected together through a conductor 6 and the pieces a w are united through another conductor 7. In each of these conductors 6 and 7 two helices 0 0 and 0",in inductive relation to each other, are included in series. The conductors of the plugcircuit are united at points intermediate ot the two helices by a bridge-wire 8, which extends to and includes the battery g, which constitutes the source of current-supply t'or signaling and for exciting the telephone-transmitters. The helices 0 0 0 0 of the repeating-coils should be of low resistance as, for example, of twenty ohms each. A battery 9 of moderate size is thus enabled to produce in the line-circuits with which the plugs are connected sutficient current to operate the substation-transmitters properly.

To repeat briefly, the telephone-line 1 2 extends t'rom the substation A to the centraloflicc switchboard, where it terminates in the two linesprings of an ordinary three-part spring-jack. One winding e of the line-relay f is included in seriesin the limb 1 of the telephone-line before it reaches the line-spring d of the spring-jack to which it is connected. A battery g, common to all the lines of the exchange, is connected in a permanentlyelosed bridge of the line, said bridge also including the impedance-coil 72 and the winding 6 of the line-relay f. The bridge referred to is made up of extensions of the telephone-line conductors leading from the terminal pieces (I (Z of the spring-jack. The bridge relation will be perceived more readily if the system be considered at a time when the telephone-line is extended by connection of the operators plug-circuit therewith at the terminal spring-jack. The line, it will be seen, extends from the substation to the spring-jack, and thence through the operators plug-circuit, and the bridge is permanently connected across theline at or near the spring-jack thereof, said bridge including the impedance-coil 72/, the battery 7, and the winding 0' of the line-relay.

The usual calling-key 72 is furnished for the operator, by which she may disconnect the plug m from its mate and connect its terminals with the poles of generator 1 of signaling-current. A listening-key r, controlling the connection of the operators telephone sets with the plug-circuit 6 7, is provided also.

The contact-sleeve n of plug m constitutes the terminal of a conductor-.9, which includes a signal-lamp 2?, which is associated with plug 122 and which is designed to indicate to the attendant the condition of the linewith which the plug is connected. The similar contactpiece of plug m is the terminal of another conductor 10, including a signal-lamp t, associated with plug 77?.

\Vhile I have for convenience of illustration indicated two batteries in the drawing, (marked 9.. and 2,) it will be understood that in practice these may be one and the same battery.

ing connection between two telephone-lines, assuming that subscriber at station A demands connection with substation B. Upon the removal of the telephone a from its switchhook the line conductors 1 and 2 are connected together through the telephone and transmitter, thus completing the circuit from battery ,0 through helices a and e of the relay and line conductor 1, returning by line conductor 2 and through impedance-coil 7b to the battery. The relay is excited and closes the local circuit 3 4, whereby the current is permitted to flow from battery Z through lamp Z, contact-points e (2* of the relay, and resistancecoil 7c. The signal-lamp Z is thus illuminated and attracts the attention of the operator, who inserts the plug m into the spring-jack Z to receive the subscribers order. It will be noted that the current heretofore existing in the line-circuit was insutficient to properly excite the substation-transmitter, since it was compelled to traverse the high-resistance helix 6' of the relay and the impedance-coil it. By the insertion of the plug m into the spring-jack a low-resistance path through the repeatingcoil helices 0 and 0 is created from battery g to the line conductors 1 and 2. It will be observed also that the helix 0 is placed in shunt about the line-coilc of the relay, whereby the latter helix is largely deprived of current through it, but that the increased current in the line-circuit traverses the other helix, 6, of the relay, thus maintaining the excitement of this instrument. The current is of course divided between the line-helix e and the noninductive resistancecoil 0 the greater portion, however, traversing the magnet-coil. By the insertion of the plug the branch 9 5, containing the supervisory lamp t, is closed and brought into shunt or parallel relation to the portion of the local circuit 3 4 containing the line-lamp Z, the resistance-coil lc'being included in the undivided portion of this circuit. The resistance of this coil should be so adjusted that the current through it when divided in this manner between the two signal lamps is insufficient to cause the illumination of either lamp. Hence by the insertion by the connecting-plug in the spring-jack the line-signal lamp Z is extinguished, while the clearing-out signal-lamp remains unlighted.

I will now trace the operation of establisl The operator now by depressing the plunger of her listening-key brings her telephone set a into connection with the plug-circuit 6 7 and receives the oral order of the subscriber at station A for the required connection. She then inserts plug m into spring-jack Z of line to station B, at the same time depressing the plunger of the calling-key to ring the bell a at that substation. Vhen the plug is insertedinto the spring-jack Z, local circuit connections similar to those just traced are made through the line-signal lamps Z and 26; but since the relay of that line is not excited the conductor 3 is interrupted, so that the line-signal Z remains dark, while the supervisory signal 5 is lighted, the entire current in the local circuit being diverted through it. At the same time the common source of ourrent-supply g is connected with the line-circuit 11 12 to station B in readiness to excite the substation-transmitter. When the subscriber at the signaled station removes his telephone from its switch-hook, the current created through the line-circuit magnetizes the relay-magn et and the latter closes the conductor 3, thus extinguishing the signal t. The subscribers, are now in position to communicate with each other. Current from battery g flows out through each line-circuit. Variations of' the resistance of the transmitter at one substation produce unclulations in the current through the same line, which are repeated through the inductive action of repeating-coil helices 0 0 and 0 0 into the other line-circuit. The telephonic circuit to station A is completed in the plugcircuit through conductor 7, coil 0, wire 8, in-

cluding battery g, coil 0 and conductor 6..

The fluctuations in magnetism of the core of the repeating-coil thus produced create in a similar circuit embracing the other portions of conductors 6 and 7 and the. windings 0 0 of the repeating-coil variations of current similar to those set up in the line to station A. This process is well understood. in the art.

Thus telephonic transmission is effected be tween the different stations. The propagation of variations in the current in the linecircuits is practically unobstructed by the presence of the magnet-coils e in the circuit,

since the variations are propagated through the non-inductive shunts about the magnetcoils. The replacement of either telephone upon its switch-hook renders the corresponding relay inert, whereby the branch, including IIO the line-lamp, is broken and the entire current in the'local circuit diverted through the supervisory signal-lamp, thus effecting its illumination. The operator is thus constantly informed by the signalst and Z of the position of the apparatus at the different substations.

WVhen both signals become illuminated, this indicates thatboth telephones have been replaced on their switch-hooks, and the connecf tion between the lines is removed.

It is apparent that my invention may be applied with advantage to systems which may differ in many respects from the one shown in the drawing, and Various modifications may be made by those skilled in the art without departing from the spirit of my invention.

I claim and desire to secure by Letters Patent 1. The combination with a telephone-line, of an electromagnet having two coils, one of said coils being included serially in the linecircuit and the other in a closed bridge of the line-circuit together with a source of signaling-current, and a signal-indicator controlled by said electromagnet, substantially as described.

2. The combination with a telephone-line, of a signal-controlling electromagnet having two magnetizing-coils, one of said coils being included serially in the line-circuit and the other in a high-resistance bridge of the linecircuit containing a source of signaling-current, means for making connection with the line, a bridge-conductor of low resistance containing a source of current adapted to be closed across the line when such connection is made, and a switch for closing or interrupting the line-circuit at the substation to operate the signals, substantially as described.

3. The combination with a telephone-line, of a switch for closing the line-circuit at the substation,spring-jacks constitutingnormally open terminals of the line, a signal-controlling electromagnet having two magnet-coils, one coil included in the line-circuit between the substation and the spring-jacks, and the other coil in a high-resistance bridge of the line-circuit with a source of signaling-current, a plug-circuit for making connection with the line, and a bridge of low resistance across the plug-circuit including said source of current, substantially as described.

4. The combination with a telephone-line and spring-jacks constituting normally open terminals of the line, of a winding of a signalcontrolling electromagnet in the line-circuit between the spring-jacks and the substation, a closed bridge of the line-circuit connected with the line intermediate of the spring-jacks and the magnet-coil, and another winding of the magnet in said closed bridge, as described.

5. The combination with a telephone-line and a switch at the substation for closing the line-circuit, of an electromagnet controlling both a line-signal permanently associated with the line and a supervisory signal temporarily associated with the line, said electromagnet having its magnet-coil interposed in the linecircuit, a bridge of the line-circuit connected with the line intermediate of the electromagnet and the spring-jacks, and a source of current in the bridge, as described.

6. The combination with a telephone-line, of spring-jacks constituting normally open terminals of the line, a relay having two magnet-coils, one of said coils being included in the line'circuit between the substation and the spring-jacks, a closed bridge of the linecircuit including a source of signaling-current, the other of said coils being included in said bridge, a subsidiary line-signal included in a local circuit controlled by a relay, and a supervisory signal adapted to be temporarily associated with the line-circuit in a local circuit also controlled by the relay, a plug-circuit for making connection with the line, the terminals of the one connecting-plug being united through helices of different inductioncoils with the poles of said source of signalingcurrent, the different members of a pair of plugs being connected with the same repeating-coils, substantially as described.

in witness whereof I hereunto subscribe my name'this 1st day of December, A. D. 1899.

FRANK R. MGBERTY.

Witnesses:

GEORGE P. BARTON, J. W. SKINKLE. 

